Fossil evidence supports at least two origins of plant roots

Roots were one of the key innovations that enabled plants to flourish on the terrestrial surface. Today roots, defined as organs that develop from a root meristem with a root cap, are present in all major groups of vascular plants suggesting that they are a defining feature of the vascular lineage. However, fossils examined in a phylogenetic context instead strongly support the hypothesis that roots evolved at least twice independently during plant evolution, once in lycophytes and once separately in euphyllophytes. This interpretation is built on a large body of fossil evidence from around the world but with a special focus on plants preserved with exceptional preservation in the famous Rhynie chert fossil locality. Investigating fossil plants in a phylogenetic context has transformed our understanding of root evolution and is key for piecing together the evolution of land plant body plan complexity.